Apparatus for non-incremental position and form measurement of moving sold bodies

Apparatus (1) for non-incremental position and form measurement of moving solid bodies (7), containing a laser Doppler distance sensor (10) in wave-length multiplexing technique with at least two different wavelengths (λ1, λ2) and with a modular fibre optic measurement head in its sensor design, with the sensor design of the laser Doppler distance sensor (10) containing two additional modules, which are connected to the measuring head by means of fibre optics:

• a light source unit (2) and a detection unit (4),
• with two laser light bundles (37) of different wavelengths (λ1, λ2) in the light source unit (2) at least being coupled into a glass fibre (24), with the bichromatic scattered light in the detection unit (4) being split into the different wavelengths (λ1, λ2) corresponding to the two measurement channels (41, 42) and subsequently being detected separately by means of two photo detectors (43, 44), and with the detection unit (4) being connected to an evaluation unit (8), in which the signal evaluation is carried out according to the principle of the laser Doppler distance sensor (10) for determination of position, speed and form of the solid body (7), characterized in that,
• the measurement head is configured as a modular passive, fibre optic diffractive miniature measurement head (30),
• which splits the bichromatic laser light bundle (37) emitted from the transmitting fibre (24) in each case into two partial beam bundles (27, 28) into the +1st diffraction order and into the −1st diffraction order using a beam-splitting grating (26), which partial beam bundles are made to superimpose in a location area by two deflection elements (29, 40) connected downstream, which location area represents the shared measurement volume (31) and that a lens (32) is arranged upstream of the beam-splitting grating (26), which
• focuses the laser light bundles (37) emitted from the transmitting fibre (24) in the environment of the measurement volume (31), with a separation of the beam waists (33, 34) in z direction being caused by the dispersion of the lens (32) in such a way that the beam waist (33) for one wavelength (λ1) λ1 is located upstream of the measurement volume (31) and the beam waist (34) for the other wavelength (λ2) is located downstream of the measurement volume (31).